Back in 1935 in Sydney, Australia, a captured shark was put on display at the beach-side aquarium at a place called Coogee. This got a lot of attention because sharks are fascinating, and this one was a tiger shark, which is dangerous, aggressive, and rarely taken alive.
People queued to see the shark, and so it was that the shark, eight days later, before a crowd of women and children, suddenly vomited up a human arm.
Needless to say this caused some excitement.
It was assumed the arm belonged to some unlucky swimmer. Then the forensics people examined it. They declared that the arm had unquestionably been severed by a sharp implement such as a cleaver before the shark had swallowed it. This shark had just coughed up evidence of a murder.
Further evidence showed that the body, or at least this arm, had been eaten by a smaller shark. The smaller shark had almost immediately been eaten by the larger shark, and the larger shark had then been taken alive by a fisherman and put in the aquarium.
You've got to feel sorry for the murderer at this point. How unlucky can you get? I really feel quite strongly that the killer had done everything right to hide his crime and if there was any justice in this world he'd have got away with it.
Incredibly, despite having been in the digestive juices of two sharks, the arm still showed a clear tattoo of two boxers, and police were able to get fingerprints. (I leave to your imagination what fun it must be to collect fingerprints from an arm that's been inside two sharks.)
The arm belonged to one Jim Smith, a small-time crook who, funnily enough, hadn't been seen recently.
It turned out that Jim Smith in addition to being a crook was also a police informer, so he had no shortage of enemies. The police followed procedure and quickly fixed on two men: a Patrick Brady, another dodgy character with whom Smith was last seen alive, and a Reginald Holmes. Holmes owned a boat building business -- which must have been very convenient for feeding any unwanted evidence to sharks -- but moreover Holmes was strongly believed to use speedboats built by his company to smuggle drugs into the country from passing cargo ships. The victim Smith had once worked for Holmes, probably driving those drug-laden speedboats, but the two had since become enemies due to a failed insurance scam.
Police questioned Brady and Holmes but couldn't get quite enough evidence. Then Holmes drove one of his speedboats into the middle of Sydney Harbour, pulled out a gun and shot himself in the head.
Except he missed. Holmes fell out of the boat and would have drowned if his arm (ironically) hadn't been caught up in a rope. He climbed back on board, by which time the water police were chasing him because the pistol shot had attracted their attention. They got him after a four hour chase.
Back on land, Holmes now agreed to testify against Brady. Which might have gone well enough, except that on the morning of the inquest, Holmes's body was found slumped over in his car with three gunshot wounds.
Meanwhile, Brady's lawyer argued that without the body, Jim Smith might still be alive, though with an arm missing. This gets points for imagination if nothing else.
Without sufficient evidence, and with Holmes dead, Brady went free. If this were a novel then the detective would have formed a close emotional bond with the shark and the two of them would have solved the crime at the last moment, but sadly I must report that the murder remains technically unsolved to this day.